Acta Vet. Brno 2012, 81: 183-188

https://doi.org/10.2754/avb201281020183

Seasonal influence on the thyroid gland in healthy dogs of various breeds in different weights

Mária Fialkovičová1, Silvia Mardzinová1, Marta Benková2, Jana Mojžišová3, Monika Gaálová4, Edina Sesztáková5

1Small Animal Clinic , University of Veterinary Medicine and Pharmacy, Košice, Slovak Republic
2Technical University of Košice, Institute of Control and Informatization of Production Processes, Košice, Slovak Republic
3Department of Epizootology and Parasitology, University of Veterinary Medicine and Pharmacy, Košice, Slovak Republic
4Small Animal Clinic, University of Veterinary Medicine and Pharmacy, Košice, Slovak Republic
5Clinic of Birds, Exotic and Free-living Animals, University of Veterinary Medicine and Pharmacy, Košice, Slovak Republic

The aim of our study was to evaluate the influence of seasonal ambient temperature on the thyroid gland function in terms of serum total thyroxine (TT4), free thyroxine (fT4), total triiodothyronine (TT3), and canine thyroid stimulating hormone (cTSH) concentrations in healthy dogs of various breeds living outdoors and to compare them with those living indoors in flats and houses. The monitoring was conducted for 5 years and our study included 162 indoor dogs and 148 outdoor dogs of both sexes from 2 to 12 years of age, categorised into 3 groups according to their body weight: large (n = 17), medium (n = 16) and small (n = 17) breeds. Comparison of the seasonal serum TT4 and fT4 concentrations in both the indoor and outdoor dogs confirmed their fluctuation in relation to the ambient temperature in all weight groups with the lowest average of TT4 and fT4 concentrations recorded in summer and the highest ones in winter. In dogs kept outdoors, the fluctuation of hormone values was significant (P < 0.05). Seasonal serum cTSH fluctuation was found to be significant (P < 0.05) only in the medium breeds living outdoors, but their concentrations did not exceed the reference ranges. The 5-year monitoring of serum TT3 in indoor and outdoor dogs of large, medium, and small breeds clearly showed that its concentrations were not influenced by varying ambient temperature. The study provides for the first time evidence that serum TT4 and fT4 concentrations in dogs kept outdoors directly depend on ambient temperature. This correlation was also expressed by mathematical equations.

References

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